LIHI Certificate #9 – Strawberry Creek Project, Wyoming

The Strawberry Hydroelectric Project includes an impoundment retained by a gravity dam, 2.3 miles of penstock a powerhouse containing three Pelton Turbines, substation and operator’s residence. Lower Valley operates the project manually in a run of river mode.

Project Name

Strawberry Creek

LIHI Certificate Number

9

LIHI Effective andExpiration Dates

October 30, 2013
October 30, 2018

Owner

Lower Valley Energy

State

Wyoming

Location

Located on Strawberry Creek in Lincoln County, Wyoming.

Installed Capacity

1.5 MW

Average Annual Generation

9.305 GWh

Facility Type

Run-of-river

FERC No.

2032

The Project dam is a reinforced concrete gravity structure with a maximum height of approximately 22 feet and total top width of 110 feet. Dam components include a 24 foot long right abutment, 40 foot long overflow spillway. 16 foot long intake/sluiceway section and a 30 toot long left abutment. Non-overflow portions of the structure (abutments & operation area) have a top elevation of7030. The overflow spillway (crest elevation= 7020) is ogee shaped and includes a downstream flip bucket and 25 foot long stilling basin. Pipe sleeves embedded into the spillway crest provide for installation of2 inch x 6 inch timber stoplogs. Normally two sets of stoplogs are in place which provides for an overflow crest elevation of approximately 7021. A 3 foot wide reinforced concrete walkway provides access across the top of the spillway. A 4 foot square sluiceway with an upstream sill elevation of7009. Provides a low level outlet for the dam. The steel sluice gate is operated manually by a hand wheel located on top of the dam.

A four inch thick reinforced granite apron originates at the dam heel and extends approximately 25 feet upstream into the reservoir. A two inch thick, reinforced granite apron extends from this point to a distance of approximately 150 feet into the impoundment and up the banks to elevation 7023.

The penstock intake is seven feet wide by four feet high with an invert elevation of7010.5. A steel slide gate operated from on top of the dam is available to isolate the penstock. Access w the penstock intake area is provided by a 2 foot by 2.5 foot manhole originating at the top of the structure. The penstock intake is protected by a trash rack comprised of vertical 2 inch x 1/4 inch steel bars spaced horizontally at 1 1/4 inches clear. Water is conveyed from the dam to the powerhouse through a 36 inch (inside diameter) mechanical joint, steel penstock. Steel thickness in the penstock walls varies from 3116 to 5/16 inches. Upstream of the powerhouse the penstock branches into three separate 20 inch diameter penstocks that later reduce to 14 inches. The penstock has a total length of approximately 11.300 feet and experiences a vertical drop of approximately 497 feet. Above ground portions of the penstock are supported by steel ring girders resting on reinforced concrete saddles. In areas of potential snow slides, the penstock is buried and typically surrounded with a 6 inch layer of select backfill and unclassified backfill. A total of ten air-inlet valves ranging in size from four to eight inches prevent the formation of vacuums within the penstock. Reinforced concrete thrust blocks (19 total) provide additional stability for the penstock at bends and at the three way branch upstream of the powerhouse.

A ten foot wide road known as Strawberry Creek Road provides access along the penstock and to the dam/impoundment. The access road is surfaced with crushed rock.

Plan dimensions of the Project powerhouse are approximately 61 feet by 32 feet. Its concrete block superstructure is supported by a reinforced concrete substructure. The powerhouse with a main floor elevation of 6512 feet houses the turbines generators and control equipment. Gate valves located within the powerhouse just upstream of the turbines, are used when necessary to isolate the units for maintenance purposes.

Located approximately 20 feet northwest of the powerhouse is the Project substation. The substation has plan dimensions of approximately 46 feet by 57 feet and is surrounded by a seven foot high chain link fence topped with three strands of barbed wire. Equipment within the substation area includes station power transformers, distribution transformers, main power transformer, and associated switchgear. Station equipment is mounted on steel superstructure or on reinforced concrete pads. The substation is surfaced with crushed rock. Overhead lines originating at the Project substation include distribution lines which serve users in the community of Bedford and transmission lines which feed the Bedford Substation.

Located adjacent to the powerhouse and within the Project boundary is a home which provides a permanent residence for the senior plant operator. Plan dimensions of the two story house at 28 feet by 31.5 feet and its attached garage is 12 feet by 21 feet. The home has a concrete block foundation and timber frame and exterior walls surfaced with siding. Electrical service for the residence is provided by the hydro project. Potable water is supplied by the Bedford Water and Sewer District. Sanitary service is provided by a local underground septic system.

Certification History

May 9, 2014: The Strawberry Creek Project has been certified for a third five year term, effective October 30, 2013 and expiring October 30, 2018.

November 18, 2013: Lower Valley Energy has submitted an application for a third term of certification of the Strawberry Creek Hydroelectric Project. The 2013 application was received on September 5, but due to administrative backlog, the certificate has been granted an extension through June 30, 2014, for review of the application.

January 22, 2009: The Strawberry Creek Hydroelectric Project was recertified as low impact for a second five year term, effective October 30, 2008 and expiring October 30, 2013.

February 27, 2004: The Strawberry Creek Hydroelectric Project has been certified as low impact. It is the first hydropower facility to earn LIHI certification in Wyoming.